Profile bodies are often still welded by hand to planar bodies, in particular curved and large-surface bodies, since prior art devices which would permit an automatic welding operation are very expensive. The problems regarding the welding of profile bodies to planar bodies arise, for instance, whenever in the making of brewing vessels, or the like, which are needed in brewhouses, heating frames consisting of profile bodies, such as angles, have to be welded onto the circumference of the wall of the brewing vessel. The diameter of the brewing vessels may range from 2 m to 7 m. It is thus troublesome to weld profile bodies extending on the outer circumference as heating frames. Nowadays the heating frames are normally attached to the outer wall in prefixed fashion, and a circumferential welding operation which is carried out by hand is then performed in general. The problems equally arise when such heating frames are to be welded in the form of profile bodies onto the bottom, in particular onto a bulging or curved bottom.